const History& h, SearchStack* ss) : pos(p), H(h) {
int searchTT = ttm;
ttMoves[0].move = ttm;
- finished = false;
lastBadCapture = badCaptures;
pinned = p.pinned_pieces(pos.side_to_move());
else if (d == Depth(0))
phasePtr = QsearchWithChecksPhaseTable;
else
+ {
phasePtr = QsearchWithoutChecksPhaseTable;
+ // Skip TT move if is not a capture or a promotion, this avoids
+ // qsearch tree explosion due to a possible perpetual check or
+ // similar rare cases when TT table is full.
+ if (ttm != MOVE_NONE && !pos.move_is_capture_or_promotion(ttm))
+ searchTT = ttMoves[0].move = MOVE_NONE;
+ }
+
phasePtr += !searchTT - 1;
go_next_phase();
}
case PH_NONCAPTURES:
lastMove = generate_noncaptures(pos, moves);
score_noncaptures();
- sort_moves(moves, lastMove);
+ sort_moves(moves, lastMove, &lastGoodNonCapture);
return;
case PH_BAD_CAPTURES:
case PH_EVASIONS:
assert(pos.is_check());
lastMove = generate_evasions(pos, moves);
- score_evasions();
+ score_evasions_or_checks();
return;
case PH_QCAPTURES:
return;
case PH_QCHECKS:
- // Perhaps we should order moves move here? FIXME
lastMove = generate_non_capture_checks(pos, moves);
+ score_evasions_or_checks();
return;
case PH_STOP:
- lastMove = curMove + 1; // hack to be friendly for get_next_move()
+ lastMove = curMove + 1; // Avoids another go_next_phase() call
return;
default:
piece = pos.piece_on(from);
hs = H.move_ordering_score(piece, to);
- // Ensure history is always preferred to pst
+ // Ensure history has always highest priority
if (hs > 0)
- hs += 1000;
+ hs += 10000;
- // pst based scoring
- cur->score = hs + pos.pst_delta(piece, from, to).mg();
+ // Gain table based scoring
+ cur->score = hs + 16 * H.gain(piece, to);
}
}
-void MovePicker::score_evasions() {
+void MovePicker::score_evasions_or_checks() {
// Try good captures ordered by MVV/LVA, then non-captures if
// destination square is not under attack, ordered by history
// value, and at the end bad-captures and non-captures with a
Move m;
int seeScore;
+ // Skip if we don't have at least two moves to order
+ if (lastMove < moves + 2)
+ return;
+
for (MoveStack* cur = moves; cur != lastMove; cur++)
{
m = cur->move;
if ((seeScore = pos.see_sign(m)) < 0)
- cur->score = seeScore;
+ cur->score = seeScore - HistoryMax; // Be sure are at the bottom
else if (pos.move_is_capture(m))
cur->score = pos.midgame_value_of_piece_on(move_to(m))
- pos.type_of_piece_on(move_from(m)) + HistoryMax;
/// are no more moves left.
/// It picks the move with the biggest score from a list of generated moves taking
/// care not to return the tt move if has already been searched previously.
+/// Note that this function is not thread safe so should be lock protected by
+/// caller when accessed through a shared MovePicker object.
Move MovePicker::get_next_move() {
break;
case PH_NONCAPTURES:
+
+ // Sort negative scored moves only when we get there
+ if (curMove == lastGoodNonCapture)
+ insertion_sort(lastGoodNonCapture, lastMove);
+
move = (curMove++)->move;
if ( move != ttMoves[0].move
&& move != ttMoves[1].move
}
}
-/// A variant of get_next_move() which takes a lock as a parameter, used to
-/// prevent multiple threads from picking the same move at a split point.
-
-Move MovePicker::get_next_move(Lock &lock) {
-
- lock_grab(&lock);
- if (finished)
- {
- lock_release(&lock);
- return MOVE_NONE;
- }
- Move m = get_next_move();
- if (m == MOVE_NONE)
- finished = true;
-
- lock_release(&lock);
- return m;
-}